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Theory and technology of enhanced oil recovery by gas and foam injection in complex reservoirs
Get PDFTo meet the growing energy demand and ensure national energy security, improving the recovery rate of developed oil fields and tapping into their remaining oil potential have become important ways to stabilize crude oil production. Given the constraints posed by the intricate nature of reservoir formation conditions and the properties of crude oil, including high viscosity, significant heterogeneity, and low permeability, certain techniques find it challenging to be effectively utilized. In view of this, this article introduces enhance heavy oil recovery by in-situ generated foamy oil, foam flooding in deep fractured vuggy reservoirs, and a new CO2 responsive fracturing foam fluid, respectively. These results can provide constructive conclusions and suggestions for the study of theories and methods of enhanced oil recovery by gas and foam injection in complex reservoirs.Document Type: PerspectiveCited as: Chen, H., Wei, B., Zhou, X., Zhu, J., Xu, Z., Fan, Y. Theory and technology of enhanced oil recovery by gas and foam injection in complex reservoirs. Advances in Geo-Energy Research, 2025, 15(3): 181-184. https://doi.org/10.46690/ager.2025.03.0
Experimental and numerical challenges in multiscale study on geomechanical and hydrological systems
Get PDFCross-scale studies in geomechanical and hydrological systems employ a variety of approaches, either experimental, simulation or theoretical, each characterized by corre sponding scale-specific methodologies. This perspective identifies and discusses challenges encountered at various scales, ranging from molecular to field scale, and examines issues related to integrating these scales. It highlights discrepancies in resolution and data compatibility, emphasizing the necessity for improved scale transition techniques. Insights and recommendations are proposed for future research to enhance multiscale modeling frameworks. These suggestions are crucial for bridging knowledge gaps on geological systems and improving the analyses accuracy for better engineering applications or earth system modelling.Document Type: PerspectiveCited as: Guo, Z., Liu, L., Liu, Z., Shen, X., Lei, L. Experimental and numerical challenges in multiscale study on geomechanical and hydrological systems. Advances in Geo-Energy Research, 2025, 15(2): 95-98. https://doi.org/10.46690/ager.2025.02.0
Simulation of CO2 enhanced oil recovery and storage in shale oil reservoirs: Unveiling the impacts of nano-confinement and oil composition
Get PDFCO2 injection into oil reservoirs is expected to achieve enhanced oil recovery along with the benefit of carbon storage, while the application potential of this strategy for shale reservoirs is unclear. In this work, a numerical model for multiphase flow in shale oil reservoirs is developed to investigate the impacts of nano-confinement and oil composition on shale oil recovery and CO2 storage efficiency. Two shale oils with different maturity levels are selected, with the higher-maturity shale oil containing lighter components. The results indicate that the saturation pressure of the lower-maturity shale oil continues to increase with increasing CO2 injection, while that of the higher-maturity shale oil continues to decrease. The recovery factor and CO2 storage rate for higher-maturity shale oil after CO2 huff-n-puff are 12.02% and 44.76%, respectively, while for lower-maturity shale oil, these are 4.41% and 69.33%, respectively. These data confirm the potential of enhanced oil recovery in conjunction with carbon storage in shale oil reservoirs. Under the nano confinement impact, a decrease in the oil saturation in the matrix during production is reduced, which leads to a significant increase in oil production and a significant decrease in gas production. The oil production of the two kinds of shale oil is comparable, but the gas production of higher-maturity shale oil is significantly higher. Nano-confinement shows a greater impact on the bubble point pressure of higher-maturity shale oil and a more pronounced impact on the production of lower-maturity shale oil.Document Type: Original articleCited as: Song, Y., Song, Z., Chen, Z., Mo, Y., Zhou, Q., Tian, S. Simulation of CO2 enhanced oil recovery and storage in shale oil reservoirs: Unveiling the impacts of nano-confinement and oil composition. Advances in Geo-Energy Research, 2024, 13(2): 106-118. https://doi.org/10.46690/ager.2024.08.0
Accurate stress measurement using hydraulic fracturing in deep low-permeability reservoirs: Challenges and research directions
Get PDFAlthough there is increasing recognition of the significance of deep in-situ stress measurement for the safe and efficient exploitation of geo-energy in deep low-permeability reservoirs, accurate measurement of deep stresses using the hydraulic fracturing technique still requires substantial enhancement. In this work, the major challenges in the precise hydraulic fracturing stress measurement in deep low-permeability reservoirs are pointed out, including high rock temperature, high pore pressure, fracturing mechanism, rock tensile strength, and drilling conditions. Under such circumstances, several future research directions are proposed accordingly. These involve the thermal-pore-elastic effect, downhole sensors and flow meters, appropriate indoor tensile strength test methods, new stress calculation methods, hybrid test techniques, and refined coupled numerical models. The future research recommendations will provide several fresh perspectives for geo-energy development in deep low-permeability reservoirs in subsequent stages.Document Type: PerspectiveCited as: Li, P., Liu, Y., Cai, M., Miao, S., Dai, L., Gorjian, M. Accurate stress measurement using hydraulic fracturing in deep low-permeability reservoirs: Challenges and research directions. Advances in Geo-Energy Research, 2024, 14(3): 165-169. https://doi.org/10.46690/ager.2024.12.0
Parameters optimization of storage capacity of hole-bottom freezing sampling technique for natural gas hydrates
Get PDFThe coolant must be pre-stored in the sampler before the freezing procedure for natural gas hydrate sampling is applied. The coolant’s storage capacity throughout the sampler-lowering procedure is crucial to ensure successful sampling. In this study, the key factors influencing storage capacity were coolant density, dry ice specific surface area, ambient pressure, and temperature difference. An orthogonal method was used to analyze each factor’s level of influence and potential action processes. The results indicated that ambient pressure, specific surface area, coolant density, and temperature difference all had significant impact. Ambient pressure affects the phase-change path of dry ice, and high pressure increases the likelihood of dry ice melting, greatly reducing latent heat. The larger specific surface area could help to generate a compact dry ice layer to protect the interior, but it may cause cold energy loss during the freezing process. Dry ice, with a smaller specific surface area, may be a better option. Low-temperature alcohol can separate the dry ice layer from the surrounding environment, allowing for heat exchange. However, a low coolant density may promote heat exchange between the alcohol layer and surrounding environment, resulting in the loss of dry ice. The appropriate coolant formulation comprised of a mixture of 2.5 kg of granular dry ice and 1 L of alcohol, temperature difference maintained at 105 K, and the working pressure of 0.1 MPa.Document Type: Original articleCited as: Lei, J., Guo, W., Yang, X., Zhang, P., Jia, R., Wang, Y. Parameters optimization of storage capacity of hole-bottom freezing sampling technique for natural gas hydrates. Advances in Geo-Energy Research, 2024, 12(1): 66-76. https://doi.org/10.46690/ager.2024.04.06
Pore evolution modeling in natural lacustrine shale influenced by mineral composition: Implications for shale oil exploration and CO2 storage
Get PDFDescribing the organic-inorganic pore evolution influenced by mineral composition is crucial for characterizing shale oil storage capacity and flow in shale, and it also helps predict storage capacity for sequestered CO2. Using laboratory pyrolysis experiments to artificially mature shale samples at relatively high temperatures and short times, this study compares a series of natural samples with different thermal maturations, which can better reflect the real underground pore evolution. A total of 30 natural shales spanning from low to high maturity were collected from the Cretaceous Qingshankou Formation of the Songliao Basin, and the analysis results revealed four main typical shales, namely argillaceous shale, felsic shale, calcareous shale, and mixed shale. The existence of clay minerals, quartz and feldspar promote the development of > 50 nm pores, while 0-20 nm pores are mainly developed in clay minerals and organic matter. When the content of total organic carbon is less than 2.5 wt.%, it displays a positive correlation with the specific surface area, but the correlation becomes negative for samples with a content of total organic carbon greater than 2.5 wt.%. The organic pores are most developed at the peak oil maturity, while inorganic pores are most developed during the oil window, and tend to be stable at high maturity. Argillaceous shale in the high maturity stage may be favorable for petroleum exploration in the Qingshankou Formation of the Songliao Basin. Mixed shale and calcareous shale may not be conducive to the short-term storage of CO2 due to strong reactions with CO2 at the beginning. On the other hand, argillaceous shale and felsic shale may be conducive to the long-term storage of CO2.Document Type: Original articleCited as: Wang, L., Liu, B., Bai, L., Yu, Z., Huo, Q., Gao, Y. Pore evolution modeling in natural lacustrine shale influenced by mineral composition: Implications for shale oil exploration and CO2 storage. Advances in Geo-Energy Research, 2024, 13(3): 218-230. https://doi.org/10.46690/ager.2024.09.0
Solitonic connections in capillarity theory: A review
Get PDFA review is presented here of research to date on the application of model parameter-dependent constitutive laws for which capillarity systems admit underlying solitonic structure with their characteristic key properties such as invariance under Bäcklund transformations and admittance of Painlevé reduction. The classical Korteweg capillarity system and its extensions are considered. Reductions to the canonical solitonic nonlinear Schrodinger and its resonant nonlinear Schrödinger equation extension containing a de Broglie-Bohm potential are exhibited in turn for certain model constitutive relations. A capillarity analogue of the classical Kármán-Tsien model law of gasdynamics is shown to have a key role in such canonical reductions. A novel geometric link between a Korteweg capillarity system and the classical Da Rios system of hydrodynamics is recorded. Invariance of capillarity systems under multi-parameter Bäcklund transformations is detailed and applied. Gausson and q-gaussion phenomena in certain capillarity systems is described with concomitant classes of exact solutions. A Lagrangian encapsulation of a Korteweg capillarity system is presented whereby reduction is made to the canonical Boussinesq equation.Document Type: Invited reviewCited as: Rogers, C. Solitonic connections in capillarity theory: A review. Capillarity, 2024, 12(3): 80-88. https://doi.org/10.46690/capi.2024.09.0
Evaluation of immiscible two-phase quasi-static displacement flow in rough fractures using LBM simulation: Effects of roughness and wettability
Get PDFRoughness and wettability of the fracture surface have crucial effects on the two-phase flow properties in many applications involving fractured rock. The immiscible quasi-static displacement flow is widely concerned in porous media, but this phenomenon has been rarely explored in rough-walled fractures. In this study, based on fractal theory and a matched fracture model, three-dimensional fractures with different roughness surfaces and uniform aperture distribution are generated. The lattice Boltzmann-based multicomponent Shan-Chen model is employed to simulate the quasi-static drainage process under various wettability conditions through rough fractures. In fractures with greater roughness and stronger wettability, the displacement process is usually more unstable with more tortuous invasion fronts, which leads to larger entry pressure and displacement resistance. Accordingly, more residual saturation of the wetting phase and lower displacement efficiency occurs under the same capillary pressure. During the invasion process, because of the transverse and delaying development of displacement fronts, the frontmost position is sometimes almost unchanged, while the wetting phase saturation sharply decreases showing a “step-like” type curve. The residual capture patterns are generally divided into two types: “isolated trapping” capture located in areas with drastic undulations of surface, and “water film” capture adsorbed to the fracture surface. Stronger wettability induces more second captures due to the greater adsorption of wetting phase to the fracture wall. A continuous increase in capillary pressure has no apparent effect on the variation in wetting phase saturation when it is greater than the entry pressure, and the first corner on the left side of capillary pressure-wetting phase saturation curves is relatively sharp.Document Type: Original articleCited as: Zhou, X., Sheng, J., Ye, Z. Evaluation of immiscible two-phase quasi-static displacement flow in rough fractures using LBM simulation: Effects of roughness and wettability. Capillarity, 2024, 11(2): 41-52. https://doi.org/10.46690/capi.2024.05.0
Whole petroleum system theory and new directions for petroleum geology development
Get PDFAs the global petroleum exploration domain gradually shifts from conventional to unconventional hydrocarbon resources, the classical petroleum system theory faces new challenges in terms of guiding the deepening exploration practices in the petroleum industry. After years of research, Chengzao Jia proposed the whole petroleum system concept and established an orderly distribution model for the coexistence of conventional and unconventional petroleum, which provides a new theoretical framework for the joint assessment and integrated exploration of conventional and unconventional petroleum resources. In this context, the 1st International Symposium on Whole Petroleum System Theory and New Directions for Petroleum Geology Development was held in Beijing in October 2-3, 2023. The theme was “Whole petroleum system theory and new frontiers in petroleum exploration”. Experts engaged in in-depth discussions on the progress of whole petroleum system theory and development directions of petroleum geology; they systematically reviewed the new theory developments and advances in sequence stratigraphy, tight oil and gas, shale oil and gas reservoir characteristics, genetic mechanisms, and development mechanisms. The conference also proposed unified genetic models for conventional and unconventional petroleum resources, and novel methods and technologies for joint assessment. Furthermore, it also included case studies on the whole petroleum system in clastic and carbonate formations in oil and gas basins, challenges, opportunities, and new directions in the development of petroleum geology. This symposium provided a valuable opportunity for the petroleum geology community to gain a deep understanding of the “whole petroleum system theory” and to summarize and refine the development directions of petroleum geology. Undoubtedly, this event contributes to the advancement of the whole petroleum system theory, guiding the development of petroleum geology theory and further promoting the joint assessment and integrated future development and utilization of conventional and unconventional petroleum resources.Document Type: PerspectiveCited as: Hu, T., Pang, X., Jiang, F. Whole petroleum system theory and new directions for petroleum geology development. Advances in Geo-Energy Research, 2024, 11(1): 1-5. https://doi.org/10.46690/ager.2024.01.0
Effect of silicone oil contamination on imbibition characteristics of liquid through porous media
Get PDFSpontaneous imbibition is a common phenomenon in oil and gas reservoir extraction, environmental engineering and biomedicine. Studies generally assume that solid matrices possess smooth and clean surfaces. However, in most practical research scenarios, solid surfaces become contaminated, obscuring their inherent wettability. This research investigates the impact of silicone oil contamination on spontaneous imbibition characteristics. Spontaneous imbibition experiments were conducted using microporous filter membranes under silicone oil contamination. The results indicate that silicone oil contamination significantly prolongs the complete saturation time. Compared to uncontaminated membranes, contamination for 5, 10 and 15 days results in an increase in saturation time of 37.5%, 68.75% and 112.5% respectively. The spontaneous imbibition dynamics under silicone oil contamination still follow the form of the classical Lucas-Washburn equation. Calculations show that the contact angle increases with the duration of contamination, indicating a decrease in wettability. A novel theoretical model based on the Lucas-Washburn equation is established to describe the imbibition dynamics under silicone oil contamination. The conclusions drawn from this study are of significant importance for understanding and improving the performance of paper-based microfluidic devices in contaminated environments, enhancing the efficiency of oil and gas reservoir recovery, and assessing the accuracy of groundwater monitoring under contaminated conditions.Document Type: Original articleCited as: Wang, X., Jiang, Y., Lin, J., Fan, H., Gabdullin, M., Pan, B. Effect of silicone oil contamination on imbibition characteristics of liquid through porous media. Capillarity, 2024, 13(3): 53-59. https://doi.org/10.46690/capi.2024.12.0